Method of separating the valuable portions of the tailings produced in the treatment of



UNITED STATES PATENT OFFICE.

ROBERT E. BOORAEM, OF BUTTE, MONTANA.

METHOD OF SEPARATING THE VALUABLE PORTIONS. OF THE TAILINGS PRODUCED INTHE TREATMENT OF ORES.

SPECIFICATION forming part of Letters Patent No. 420,432, dated February4, 1890.

Application filed June 1, 1889. Serial No. 312,906. (No specimens.)

To all whom it may concern:

Be it known that 1, ROBERT E. BOORAEM, a citizen of the United States,residing at Butte, in the county of Silver Bow and'Territory of Montana,have invented'certain new and useful Improvements in Methods ofSeparating the Valuable Portions of the Tailings Produced in theTreatment of Ores; and I do hereby declare the following to be a full,clear, and exact description of the invention, such as will enableothers skilledvin the art to which it appertains to make and use thesame.

My invention relates to an improvement in the method of separation ofvaluable portions of the tailings produced by the initial process oftreatment of ores of precious metals, and the object of the same is toseparate such portion of the mass of tailings resulting fromsaid'process without subjecting the same to regrinding in pans or othermachinery, and so save the larger portion of the tailings while the'mass is still Wet without allowing the same to accumulate for thepurpose of working over. Thus, for example, in the ordinarysilver-milling operations and amalgamation,

chlorinations, &c., the resultant tailings, being wet, are allowed tolie in the dumps for future working until alarge mass has accumulated,and in many cases the same, as a mat,

ter of fact, are never reworked, for the reason that the accumulatedmass contains such a small amount of precious metal in proportion to itsbulk that reworking of the same would be unwarranted, for as yet nosuccessful process for reworking lean tailings has been invented. I

Now, I have. discovered that when the mass of tailings resulting fromthe initial process of treating precious metals which requires the oreor pulp to be previously roasted or chlorodized is carefully examinedand assayed or subjected to other chemical examination the richerportion of the tailings is found in the form of lumps, or in theagglomerated portions of the mass By the term lumps or agglomeratedportions is meant portions of the ore or pulp of any size which islarger than the mesh of the screen of the stamp-battery in which the rawore is originally crushed. Thus, for example, if a twentylost and cannotbe separated when the tailings have become dry. They are produced in thefurnace, and especially in the rotary furnaces, where the motion of thefurnace, with the common or marine salt used therein, tends to ball thefusible particles together with the salt. These lumps in the pulpcanonly be detected when wet, and have the appearance of small pebbles, sofar as their artificial smoothness and hardness are concerned. If, now,by any convenient form of mechanical separation without reference to theparticular agencies employed, these agglomerated portions orlumps can beseparated from the mass, such portions will be found to contain all thatis of value, and the remainder maybe rejected as 'valueless. In thismanner a larger percentage of richer matter is saved than before, andhence the expense of retreatment is warranted. This is owing to the factthat the agglomeration or formation of lumps takes place during thechlorodizing or roasting process and previous to the amalgamationorleaching, and as the process of ordinary pan amalgamation consists inbringing the mercury into actual contact with the precious metals lockedup in the particles of ore, the percentage of amalgamation is less whenthe mercury does not penetrate the lumps, and the precious metal is leftunamalgamated in the latter. This may also be due to an imperfectchlorodizing in the furnace, owing to the lumped or balled condition,and any imperfection in the initial chlorodizing can be corrected afterthe lumps are separated in the second working of the same. Whereleaching is resorted to as a means of extraction, the result is similar,the chemical action of the leachingsolutions upon the hard, fused, orglazed surfaces of the agglomerated portions being much less than uponthe other portions of the mass, and the percentage of extractioncorrespondingly less. If, now, the

tailings be immediately screened or separated while they are still wetby other mechanical agenciessuch, for example, as the ordinary hydraulicseparator-it will be found that the agglomerated portions or lumps maybe readily separated and so saved, and prepared for retreatment by anyconvenient method.

It will be observed that the gist of the in.- Vention lies in theseparation of the lumps while the same are wet and as they aredischarged as waste tailings from the initial process, and it is onlypracticable to separate under such conditions, for the reason that whenthe railings have been allowed to dry, or when they are exposed to theair, the agglomerated portions slack and crumble to pieces in time andbecome lost in the entire mass, which then, asa whole, becomes usuallyof too low a grade throughout to warrant reworking. The separation ofthe lumps as a part of the initial process for immediate reworking, orfor storage of these higher-grade lumped tailings in special placesseparate from the low-grade mass, gives at once a classified productwhich is valuable.

Any method of separation may be resorted to that will permit of theseparation of the agglomerated portions or lumps while wet, and I do notlimit myself to any particular agencies for that purpose, nor do I limitmyself to the application of the invention to saving the preciousmetals; but am aware that the invention is applicable to the separationof lead, copper, or other valuable metals, should the same be associatedwith the precious metals in the lumps so saved.

In cases where water is not plentiful and power convenient the ordinaryrotary screen, largely in use throughout the WVest for sizing purposes,may be used. In cases where there is a large supply of water hydraulicseparation will be found most advantageous, as no power is required.

I claim as my invention- The hereinbefore-described method of separatingand saving the valuable portions of the tailings resultant from theinitial process of treatment of precious metals, consisting in roastingor chlorodizing the ores, then leaching or amalgamating the same, and inmep chanically separating the agglomerated portions or lumps then in thetailings while the same are still wet, as an additional step in and as apart of the initial process by suitable means, and subsequentlyreworking tho In testimony whereof I have affixed my signature, inpresence of two witnesses, this 21st day of May, 1889.

ROBT. E. BOORAEM.

\Vitncsses:

JOHN F. Foams, IIIRAM KNOWLES.

